JP6516843B2 - Method and apparatus for manufacturing a magnetic sensor device, and corresponding magnetic sensor device - Google Patents

Description

  The present invention relates to a method and apparatus for manufacturing a magnetic field sensor device, and to a magnetic field sensor device manufactured by the method according to the present invention. In particular, the present invention aims at the permanent magnetization of at least one ferromagnetic layer in a magnetic field sensor device deposited on a chip substrate, by simultaneously magnetizing a plurality of adjacent ferromagnetic layers in more than one direction It is possible to provide a high quality magnetic field sensor device with sensitivity.

Magnetoresistive sensor devices are used for resistance-based measurement of magnetic fields and thereby for indirect measurement of further physical quantities, such as distance, angle or current intensity. A sensor arrangement of this type is based on the magnetoresistance effect, wherein the application of an external magnetic field causes a change in the electrical resistance of the chip structure. Magnetic field sensor devices based on the giant magnetoresistive effect (GMR-effect) or the tunnel magnetoresistive effect (TMR-effect) are increasingly being used recently. These include thin film structures of nonmagnetic and magnetic materials in which magnetic coupling or spin effects affect the electrical resistance through the layer. In GMR and TMR based magnetoresistive layer systems, changes of up to 5% (GMR) or up to 600% (TMR) of the electrical resistance can be achieved based on the external magnetic field, respectively. The layer structure of at least two ferromagnetic layers and one insulator layer that make up the tunnel barrier so that the TMR sensor can be manufactured and electrons can tunnel through the insulator layer between the two ferromagnetic layers It is formed. In the case of a TMR sensor, the insulator layer is, for example, Al ₂ O ₃ or MgO. In the case of GMR sensors, thin conductive layers, for example Cu or Ru, are often used. The electrical resistance of the tunnel element depends on how the two ferromagnetic layers are magnetized relative to one another. The resistance is minimal if the two ferromagnetic layers are magnetized parallel to one another. When the two ferromagnetic layers are magnetized antiparallel to one another, the resistance is at a maximum. In practice, the magnetization of one of the two ferromagnetic layers is often fixed (pinned) so that the magnetization of this layer does not or only weakly reacts to the external magnetic field. This layer is referred to as a reference layer, or a pinned layer, or a permanent magnetisation layer. On the other hand, the other layer is formed such that its magnetization follows the external magnetic field in a defined manner. This layer is called the detection layer or free layer. By dividing into a reference layer and a detection layer that react differently to the external field, it is possible to obtain a change in resistance when the external field changes, and a sensitive device can be realized. The resistance dependence correlates to the angle between the magnetization direction of the detection layer, also called the “free layer”, and the magnetization direction of the reference layer, the so-called “pinned layer”.

  Thin film technology is used to produce this type of structure. Within the framework of the manufacturing method, the magnetization direction of the reference layer can be set permanently, which is often referred to as pinning. In order to pin the ferromagnetic layer, also referred to as the reference layer, the ferromagnetic layer is usually coupled to the antiferromagnetic adjacent layer. In order to set the magnetization direction, the resistive element is heated to a temperature higher than the so-called blocking temperature at which the exchange coupling between the antiferromagnetic layer and the ferromagnetic layer disappears, which is generally the temperature of the ferromagnetic layer. Lower than the Curie temperature. After being heated below the Curie temperature and above the blocking temperature, the ferromagnetic layers are subjected to an external magnetic field which forces them in a predetermined magnetization direction. The antiferromagnetic layer is held in this magnetization direction when it is cooled to a temperature lower than the blocking temperature while a magnetic field is applied.

  It is highly preferred that different pinning directions can be set individually and independently of one another on a single chip substrate so that multiple single pinning directions can be specified. In particular, Wheatstone bridges are very useful in sensor technology. It is preferred here that the four branches of the Wheatstone bridge are formed identical and differ only in the pinning direction.

  Several different solutions for producing pinned structures for the provision of magnetoresistive sensors are already known from the prior art. For example, DE 10 2012 208 882 discloses that a flat magnetic field is generated relative to the chip substrate surface such that a uniform pinning direction can be provided throughout the chip substrate. Similarly, in DE 11 2009 0011 140, an external magnetic field is applied parallel to the chip surface at a temperature of 200 ° C. to 350 ° C. in order to preset the ferromagnetic layer. For example, U.S. Pat. No. 6,501,678 B1 proposes a type of magnetic stamp that enables complex magnetic field orientation provided in a chip substrate.

  Alternatively, a current conductor can be provided on the surface of the chip substrate, or the current conductor can be deposited in a short period of time, and various local magnetic fields can be generated by the flow of current, so that It has a manufacturing method that can achieve magnetization. For example, WO 96/38738 discloses the application of pinning current with the aid of current conductors to cause the magnetization of the individual layer strips. Also, DE 195 20 206 proposes a conducting layer which carries a set-up current in order to be able to predetermine the pinning direction. Finally, US Pat. No. 5,561,368 and DE 11 201 0 03 705 propose composite current-carrying elements which allow different pinning directions to be applied on the chip substrate. Also, DE 195 20 206 discloses locally heating with a laser, while applying a magnetization direction with a conductor track, in order to be able to provide a composite pinning pattern in a magnetic field sensor device.

  In US20020180433A1, first, a soft magnetic structural element as a magnetic flux concentration element is disposed in the vicinity of the resistive element, and a chip such that all resistive elements provided with the soft magnetic structural element are pinned in the same magnetic field direction A method for pinning based on GMR or TMR is disclosed in which a pinning field is coupled parallel to the surface.

  From U.S. Pat. No. 8,715,776 B2, a resistive element separated by an insulating layer is a general pin covered or bounded by a hard magnetic layer to achieve alternate pinning in the direction of magnetization in reverse polarization. I know how to stop it. The pretreatment magnetic field is again coupled parallel to the chip substrate surface.

  JP 2010066262 A and the related DE 102008041859 A are provided with a flux concentration element which generates a magnetic field component which can be detected by the magnetoresistive element on the surface of the chip substrate when the perpendicular magnetic field components are coupled antiparallel to one another The present invention relates to a magnetic field sensor device for measuring a measured magnetic field component perpendicular to a surface.

  In US20060226940, the chip substrate is inserted at the center of the superconducting current coil so that its chip substrate surface is parallel to the magnetic field axis of the coil in order to define the pinning axis of the current coil pretreatment magnetic field parallel to the substrate surface A pinning method for a GMR resistive element is disclosed.

  In US20110151589 A1, rectangular resistive elements with a predefined length / width ratio are arranged in orthogonal rows on a chip substrate, parallel to the chip substrate to pin orthogonal resistive element rows in an orthogonal direction A method of pinning resistive elements in two orthogonal directions is disclosed in which aligned pretreatment magnetic fields are combined at a 45 ° pinning angle.

  The above-described method known from the prior art for locally pinning layer strips of magnetoresistive structures consists in fixing all resistance elements in the same direction when an external magnetic field is applied parallel to the surface of the chip substrate It has the disadvantage that very complicated conductor structures have to be arranged in order to achieve the magnetization due to the pinned setup current in order to provide different directions. If a pinned conductor structure is provided, then, during the manufacturing process, electrical connections are required, and additional process steps and thus high costs for the production of such sensors have to be expended.

  Thus, known manufacturing methods are only implemented with high cost of pinning, which is relatively uniform over large areas and with respect to unidirectionality, and the resulting sensors have low resolution accuracy and high production costs, There is a drawback that the production cost is high.

  Starting from the prior art described above, the problem to be solved is to effectively manufacture a high quality and economical miniaturized magnetoresistive sensor element. This is easy to manufacture and can be achieved by reference layers with different pinned magnetization directions. A further object of the present invention is to provide a precise and highly integrated sensor element which can measure, for example, the magnetic field in the 2D or 3D direction on a single chip substrate.

  This object is achieved by the method and apparatus according to the independent claims. A magnetoresistive sensor device according to the further main independent claim can be manufactured therewith. Advantageous embodiments are described in the dependent dependent claims.

  According to the invention, in the magnetoresistive sensor device, the following steps are performed to pin or permanently magnetize at least one ferromagnetic layer in the magnetic field sensor device deposited on the chip substrate: A manufacturing method is proposed.

  Producing on the chip substrate at least one magnetoresistive element comprising at least one ferromagnetic layer and at least one antiferromagnetic layer, the exchange coupling disappearing when the blocking temperature is reached It acts between the ferromagnetic layer.

  Depositing on the chip substrate at least one soft magnetic structural element adjacent or partially overlapping the resistive element;

  Heating the resistive element to a temperature above the blocking temperature of the material of the antiferromagnetic layer and combining with the pretreatment magnetic field.

  Cooling the resistive element to a temperature below the blocking temperature.

  It is a step of removing the pretreatment magnetic field.

  In a first step, at least one, in particular a plurality of magnetoresistive elements, preferably GMR or TMR resistance elements, having free and reference layers, are deposited on the chip substrate, the reference layers being directly exchange coupled And at least one ferromagnetic layer coupled to the adjacent antiferromagnetic layer. Also, for example, at least one soft magnetic structural element of lithographically structured nickel-iron alloy is deposited on the chip substrate adjacent to or partially overlapping the resistive element. This can be done on the chip substrate, for example, by electrogalvanic deposition, sputtering, evaporation or similar means known from chip construction. In order to align the ferromagnetic layer, a temperature higher than the blocking temperature is applied, so that the exchange interaction between the ferromagnetic layer and the antiferromagnetic layer disappears. The ferromagnetic layer is no longer pinned by the adjacent antiferromagnetic layer and acts like a free layer. Then, the field lines of the pretreatment magnetic field are combined with an external magnetic field, which will be referred to hereinafter as the pretreatment magnetic field, in the resistive element at the appropriate point to bring about the adjustable magnetization of the ferromagnetic layer based on the geometrical structure of the structural element. As it appears, it is induced by the soft magnetic structural element.

  According to the invention, the pretreatment magnetic field is coupled to the structural element perpendicularly to the chip substrate surface. An angle of up to 45 ° to the normal of the chip substrate surface may also be assumed for the largest component of the pretreatment field. Thereafter, the resistive element is cooled to a temperature lower than the blocking temperature so that the magnetization is fixed, the pretreatment magnetic field is removed, and as a result, pinning of the ferromagnetic layer is completed.

  If desired, the soft magnetic structure of the device can be removed from the chip substrate, for example, by etching, sputtering or similar selective material removal methods, before the pinning operation is complete. However, the structural elements can also be left on the chip substrate, for example as used as conductor elements, flux inducing elements or the like.

  Depending on the shape of the boundary of the soft magnetic structural element, any desired alignment of the pinned magnetic field is achieved by the stray magnetic field of the structural element in order to be able to pin discrete ferromagnetic layers in different directions. be able to. Thereby, any pinning direction can be set. Because of the pinning, the sensor element as a whole can be subjected to an external magnetic field as homogeneous as possible (equal to the pretreatment field), the individual local magnetization direction being set by the pole or boundary edge of the structural element Can. The structural element can be removed after applying the pinning field and can preferably consist of nickel iron. An insulating layer of SiN having a relatively small thickness of, for example, 30 nm to 5 μm can be provided between the resistance element and the structural element.

  The lithographic method of manufacture allows the structural element to have any extension and interface structures where a pinned stray magnetic field appears. Thus, the different pinning directions of the Wheatstone measuring bridge structure can be preset in a single process step. As a result, the non-uniformity of the material on the chip structure compensates for the resistance elements of the Wheatstone measurement bridge, for example, in a interdigitated manner and in space, so that they compensate each other by the spatial proximity of the corresponding resistance elements of the measurement structure. It is possible to construct adjacently. In particular, this can compensate for temperature dependent defects or defects in the material and improve the accuracy. A single structural element can be formed such that two or more TMR or GMR resistive elements can be pinned simultaneously.

  According to the present invention, the soft magnetic structural element is coupled with the pretreatment magnetic field perpendicular to the chip surface by the structural element, and at the position of the resistive element, in at least a part of the ferromagnetic layer of the resistive element. Are arranged to generate a magnetic field component parallel to the chip surface passing through. Thus, the pretreatment magnetic field may be a uniform magnetic field generated perpendicular to the chip substrate surface, and due to the magnetic field induced properties and the geometric design of the structural elements, the form of stray magnetic field parallel to the surface of the chip Appear at the boundary edge and pin adjacent resistor elements. This allows the resistive element to be provided with any desired pinning direction, and as a result, a single structural element can pin multiple resistive elements simultaneously.

  In an advantageous embodiment, more than one resistive element can be associated with the soft magnetic structural element in order to carry out the magnetization of at least one ferromagnetic layer of the resistive element in the same direction parallel to the chip substrate surface . Alternatively, more than one resistive element can be associated with the soft magnetic structural element in order to carry out the magnetization of at least one ferromagnetic layer of the resistive element in the opposite direction parallel to the chip substrate surface. Thus, two or more resistive elements can be associated with the structural element at the same time, and forming the magnetic poles of the structural element enables pinning in the same or different directions, in particular in antiparallel directions. Thus, the two opposite poles of the structural element can lead to a 180 ° appearance of stray field lines, so for example simultaneous pinning of the two resistive elements associated with the lower or upper half bridge of the Wheatstone measuring bridge to enable. Because the oppositely pinned resistive elements are spatially adjacent, temperature drift or material defects in the chip substrate cause the same resistance change so that they compensate each other in the measurement bridge, so that the bridge offset Is minimized. Minimizing the offset improves the accuracy of the magnetic field sensor measurement bridge. In particular, in the case of TMR resistive elements, the homogeneity of the tunnel barrier is a drawback of the manufacturing method. As the layer thickness of the tunnel barrier is contained exponentially in the resistance of the tunnel element, with a Wheatstone bridge, a slight change in the layer thickness causes a relatively large offset value of the bridge. In order to minimize this offset problem, due to the spatial proximity, the change in barrier thickness is the smallest and the bridge branches have similar structural properties as much as possible, so as close as possible two spatial branches It is advantageous to arrange.

  Advantageously, the set magnetization directions of the ferromagnetic layers of the resistive element can be parallel or antiparallel to one another, depending on the shape of the contour of the structural element and the spatial position of the resistive element with respect to the structural element .

  In an advantageous embodiment, at least two or more resistance elements can be used to form the Wheatstone measurement bridge, preferably at least one upper or lower bridge arm of the Wheatstone measurement bridge. For this purpose, in particular, using one structural element for pinning the upper bridge arm and one structural element for pinning the lower bridge arm, or simultaneously pinning the upper and lower bridge arm resistance elements. It is convenient to provide a common structural element with the poles formed differently to stop. Preferably, the resistive element forming the upper bridge arm and the resistive element forming the lower bridge arm are spatially adjacent to each other on the chip substrate.

  Advantageously, the resistive elements are aligned such that they form a GMR layer system. A GMR layer system (giant magnetoresistive layer system) means a structure consisting of at least two ferromagnetic layers separated by a nonmagnetic metal layer. Indirect exchange coupling, so-called RKKY interaction coupling, acts between two ferromagnetic layers. The resistance of the GMR resistive element depends on the angle between the magnetization directions of the ferromagnetic layers.

  Alternatively, the magnetic field sensor device can also comprise resistive elements forming a tunnel resistive layer system (TMR layer system). The TMR system is based on a thin insulator with a layer thickness of 0.5 to 3 nm provided between two ferromagnetic layers, so that electrons can tunnel between the ferromagnetic layers. Thus, the proposed manufacturing method can be used particularly easily and economically for the manufacture of GMR magnetic field sensors or TMR magnetic field sensors. This makes it possible to manufacture magnetic field sensor devices for compass applications or for distance measuring devices, angle measuring devices etc.

  In an advantageous embodiment, at least one boundary edge of the soft magnetic structural element may extend substantially parallel or tangential to the boundary edge of the resistive element, the resistive element being at least partially by the soft magnetic structural element The areas overlap, or are encompassed thereby, and the overlap has a size of 5 μm or less. Therefore, it is proposed to provide at least one boundary edge of the soft magnetic structural element parallel or tangential to the contour of the resistive element so that the magnetic field induced by the structural element and appearing at the boundary edge directly enters the resistive element, Thus, the high pinning effect of the ferromagnetic layer can be induced. This can improve the coupling of the pinned field from the structural element to the resistive element and achieve a reliable alignment of the ferromagnetic layers.

  In an advantageous embodiment, the pretreatment magnetic field can penetrate the chip substrate substantially perpendicularly to the chip substrate surface, and the magnetic stray field in the region of the boundary edge of the soft magnetic structural element is the surface of the chip substrate Or substantially sufficiently aligned parallel to the surface of the chip substrate. Thus, the magnetic field lines can be aligned at an angle of up to 45 ° with the chip substrate surface. It is proposed that the pretreatment magnetic field can be aligned perpendicular to the chip substrate by the structural element, in the region of the boundary edge, the magnetic stray magnetic field scatters parallel to the chip substrate, the stray magnetic field is only a locally limited effect The magnetically opposite pole is disposed below the chip substrate so as to be guided to the opposite pole of the magnetic field generator through the chip substrate. In this way, many different aligned stray magnetic fields can be generated close to each other by the structural elements so that different pinning directions can be provided at high density on the chip.

  According to an advantageous embodiment, the soft magnetic field of the emerging magnetic stray field is preferably soft-magnetic so that it is induced and amplified by salient pole shoes or flux-induced notches in the structural element. Structural elements can be formed. In order to specifically induce and bundle the magnetic field in the soft magnetic structural element so that a high stray magnetic field can appear at the necessary boundary edge, the structural element is such that a protruding pole shoe is formed, or an edge, It is proposed to be formed along the boundary edge and also on the surface facing the chip substrate surface so that flux-induced notches such as steps or roundings are provided. This enables relatively high pinning field strength at the boundary edge and provides reliable pinning with high quality and stable quality.

In an advantageous embodiment, the resistive element can be insulated from the soft magnetic structural element by an insulating layer, in particular by a SiN layer or an Al ₂ O ₃ layer having a thickness of 30 nm to 5 μm. In particular, the intermediate insulating layer between the chip substrate of the resistive element and the structural element simplifies the deposition of the structural element and, in particular, when the pinning is completed without damaging the resistive element or the chip substrate Can be easily removed. This prevents contamination and damage on the chip substrate. SiN or Al ₂ O ₃ layers with relatively thin thicknesses of 30 nm to 5 μm up to 10 μm easily deposit and protect the magnetic field sensor chip before and during deposition and when removing the soft magnetic structural element can do.

  In an advantageous embodiment, the soft magnetic structural element is preferably electroplated by depositing or constructing a soft magnetic material layer of NiFe, in particular having a layer thickness of 1000 nm to 20 μm, on the chip substrate. Alternatively, it can be manufactured by gas deposition methods or lithographic structuring methods for structuring individual soft magnetic structures. In electroplating, a seed layer on which the light structures are deposited is usually deposited first. The structure is then deposited by a galvanisation layer and the seed layer is then removed. The structural element is proposed to be deposited by depositing NiFe with a layer thickness of 1000 nm to 20 μm, in particular by means of lithographic structuring and electroplating or gas deposition. Here, after deposition over a large area, separate structures are formed, for example to form predetermined pole shoes etc., and lithographic structuring to form the required shape of the boundary contours of the structural elements. It can be implemented. This allows the use of proven technology to deposit structural elements, which can be easily integrated into existing manufacturing processes without increasing costs and spending time .

  Advantageously, the soft magnetic component can be removed from the chip substrate when the pinning process is complete. Next, structural elements that can be removed without leaving residue after coupling the pinning field are used only as a manufacturing and sacrificial layer. Thus, without limiting the sensor structure, the design and shape of the magnetic field sensor structure can be chosen regardless of the shape of the coupling structure element. Thus, the shape of the structural element can be optimally selected for the coupling process of the pinned field without having to compromise on the further use of the structural element.

  In the same aspect, the present invention relates to a magnetic field pretreatment apparatus for magnetic pretreatment of resistive elements of a magnetic field sensor apparatus deposited on a chip substrate. The magnetic field pretreatment apparatus includes an oven and a magnetic field generator having a magnetic pole face and an opposing magnetic pole face inside the oven, and a resistive element disposed on the chip substrate by the pretreatment magnetic field aligned vertically to the chip substrate surface In order to achieve a magnetic pre-treatment, in particular pinning, of at least one soft magnetic structural element at least one chip substrate can be arranged between the pole face and the opposite pole face. Preferably, multiple chip substrates or wafers are pinned at the same time. The oven is suitable for setting a temperature above the blocking temperature of the individual layer strips of the resistive element and below the Curie temperature in order to achieve pinning by applying an external pretreatment magnetic field. After the resistive element is deposited on the chip substrate surface, it is heated and pinned in a magnetic field pretreatment apparatus. A pretreatment magnetic field can be applied during all heating and cooling processes, or is selectively turned on when it reaches a predefined temperature, and turned off when it falls below a predefined temperature. It can be done. Alternatively, the chip substrate or wafer to be pinned can be removed from the magnetic field device to remove the external pinned magnetic field. After this, the structural elements can be removed and the completion of the magnetic field sensor device can take place in a further process step.

  In an advantageous embodiment, the magnetic field generator may comprise a permanent magnet disposed in the oven, and the strength of the pretreatment magnetic field is determined by the air gap adjustment device between the permanent magnet and the pole face and the opposing pole face. The adjustable air gap between can be set. If the pretreatment magnetic field is provided by a permanent magnet, this type of magnetic field generator can be used in any oven without the need to supply additional power. In this case, in order to set the strength of the pretreatment magnetic field, the strength of the magnetic field can be set by adjusting the air gap using an air gap adjusting device. The magnetic field is permanently applied during the heating and cooling process, and its strength can be changed, for example, by changing the air gap. The oven is turned so that the prefabricated chip substrate with the soft magnetic structural element can be placed between the pole face and the opposing pole face to achieve reliable pinning of the magnetic field sensor device. It is heated to a temperature higher than the blocking temperature of the ferromagnetic layer and maintained at a temperature lower than the Curie temperature of the ferromagnetic layer.

  Finally, in a further same aspect of the invention, it is proposed that a magnetic field sensor device for detecting a component of at least one external magnetic field comprises at least one magnetoresistive element. The magnetic field sensor device is manufactured according to one of the possible embodiments of the manufacturing method described above.

  Further advantages can be understood from the presented description of the drawings. Exemplary embodiments of the invention are illustrated in the drawings. The drawings, the description and the claims contain numerous features in combination. Conveniently, one skilled in the art considers these features alone and combines them to form meaningful further combinations.

FIG. 1a shows, in a perspective view, a first embodiment of the manufacturing steps according to the manufacturing method according to the invention. FIG. 1 b shows a magnetic stray field for pinning a resistive structure according to the fabrication steps of the method according to the invention. FIG. 2 shows a diagram of different soft magnetic structural elements used in an embodiment of the method according to the invention. FIG. 3 shows a chip structure with a soft magnetic structural element for producing the measuring device according to the invention. FIG. 4a shows a schematic circuit diagram of an embodiment of the measuring device according to the invention. FIG. 4 b shows the chip structure of an embodiment of the measuring device according to the invention. FIG. 5 shows a diagram of an exemplary layer structure that is advantageous for the method of the present invention. FIG. 6 schematically shows an embodiment of a magnetic field pretreatment apparatus according to an exemplary embodiment of the present invention. FIG. 7 shows, in a perspective view, an embodiment of a magnetic field pretreatment device according to the invention. FIG. 8 schematically shows, in a side view, the steps of pinning according to different embodiments of the invention. FIG. 9 shows a cross-sectional view of the structural setup after depositing the soft magnetic structural element within the framework of an embodiment of the method according to the invention.

  In the drawings, the same elements are denoted by the same reference numerals.

  A perspective schematic view of the pinned resistive element 14 of the magnetic field sensor device 10 is shown in FIG. The magnetic field sensor device 10 includes a chip substrate 12 on which the resistive element 14 is disposed. The resistive elements 14 consist of a plurality of single thin ferromagnetic and antiferromagnetic layers that can be stacked on top of each other and connected to form a Wheatstone measurement bridge. The pretreatment magnetic field Hz 38 aligned perpendicular to the surface 36 of the chip substrate 12 is used for the magnetic pre-alignment, so-called pinning, of the ferromagnetic layer of the resistance element 14. The pretreatment magnetic field Hz 38 is transmitted by the magnetic pole (not shown), penetrates the chip substrate 12 and is absorbed again by the opposing magnetic pole surface 58 disposed below the chip substrate 12. The pretreatment magnetic field Hz 38 penetrates perpendicularly to the soft magnetic structural element 18 and is aligned perpendicular to the structural layer surface 44. Due to the distance from the chip substrate and the increased magnetic conductivity through the resistive element 14, the structural element 18 is such that the pretreatment magnetic field 38 appears at the boundary edge 20 parallel to the chip surface 36 and penetrates the resistive element 14. A pretreatment magnetic field 38 is induced. The improved penetration of the resistive element 14 is achieved, in particular, by setting a temperature higher than the blocking temperature of the antiferromagnetic layer of the resistive element, so that an improvement of the flux induction through the resistive element 14 is possible. It will happen. The boundary edge 20 of the structural element 18 overlaps the boundary edge 22 of the resistive element 14.

  In FIG. 1b, a cross-sectional view of the corresponding magnetic field is shown, and the magnetic flux scattering at the boundary edge 20 and the corresponding stray magnetic field 46 of the structural element 18 affected by the resistive element 14 are shown. It can be clearly seen that the boundary edge 20 of the structural element 18 overlaps the boundary edge 22 of the resistive element 14. Thus, the full width of the resistive element 14 is transmitted by the magnetic field having a component in the chip plane. Finally, the field lines are advanced through the chip substrate 12 to the opposing pole faces 58, so that different pinning field directions are set depending on the alignment of the boundary edge 20 of the structural element 18 on the chip substrate 12. Make it possible.

  In FIGS. 2a-2c, different further embodiments of possible soft magnetic structural elements 18 are shown in perspective. These are, for example, an octagonal layer strip according to FIG. 2a, a semicircular layer strip according to FIG. 2b, an angled layer strip according to FIG. To be realized. The structural element 18 can have a plurality of boundary edges 20 that are angled or bent relative to one another in the form of a polygon. The pretreatment magnetic field Hz 38 is perpendicular to the structural layer surface 44, and the stray magnetic field 46 perpendicular to the boundary edge 20 of the structural element 18 appears substantially parallel to the chip substrate surface. This allows any predetermined pinning direction to be set for manufacturing the magnetic field sensor device 10.

  FIGS. 3 and 4 show two composite Wheatstone measurement bridges for measuring the two orthogonal magnetic field components X and Y of the magnetic field sensor device 10. The pinning step of the magnetic field sensor device 10 is illustrated in FIG. 3 and, for example, a plurality of resistive elements 14 of TMR resistive elements are disposed on the chip substrate surface 36 of the chip substrate 12. The soft magnetic structural element 18 and the boundary edge 20 at least partially overlapping with the boundary edge 22 of the resistive element 14 are deposited so as to partially overlap the boundary edge 22 of the resistive element 14. By applying a pretreatment magnetic field aligned vertically to the chip substrate surface 36, a stray magnetic field 46 of the structural element 18 is generated, as indicated by the small arrows, to pin the resistive element 14.

  FIG. 4a shows a circuit diagram of one of the two Wheatstone measuring bridges of the magnetic field sensor device according to FIG. The Wheatstone measuring bridge 24 consists of four individual bridge resistors 26 each of which consists of two resistive elements 14 and thus in each case each of the bridge resistors 26 is connected in series. It comprises resistance elements 26a and 26b. Bridge resistor elements 26a and 26b are pinned in the same direction. Current can be supplied to the measurement bridge 24 by means of supply pins B1a and B1b 40. The bridge resistors 26 of the upper measuring bridge 30 of the two bridge arms are pinned in the opposite direction. The same applies to the bridge resistor 26 of the lower measurement bridge 28. The bridge resistors 26 of the upper measurement bridge 30 and the lower measurement bridge 28 are likewise pinned with opposing senses. By applying an external magnetic field, the corresponding resistance values of the bridge resistances of the upper and lower measuring bridge are influenced to produce a significant voltage difference at the measuring contacts B2a, B2b 40, the resistance change being the magnitude and / or the external magnetic field Allows to guess the angle. As shown in FIG. 3, two sets of resistive elements 14 connected to the bridge resistor 26 are disposed on one plane of the chip substrate 12, and the resistive elements 14 are disposed at 90 ° to each other for 2D measurement 2 Provided on one measuring bridge 24.

  FIG. 4 b shows the circuit configuration as schematically shown in FIG. 4 a after removing the soft magnetic structural element 18 and electrically connecting the individual resistive elements 14. Two measuring bridges 24x and 24y, which can be pinned in the X and Y directions by means of a constant pretreatment magnetic field, are arranged on the common chip substrate 12. For this purpose, as shown in FIG. 3, a plurality of soft magnetic structural elements 18 are provided, in each case two adjacent resistance elements 26a, 26b can be pinned with the opposing sense, and two measuring bridges They are offset by 90 ° to each other with respect to 24x, 24y. A common pinning process by placing soft magnetic structural elements and introducing a uniform pretreatment magnetic field enables reliable pinning to be achieved very easily, temperature drift or non-uniformity in the chip substrate The associated resistive elements 14 of the measuring bridge 26 are spatially adjacent so that the gender can compensate each other. As a result, it is possible to provide a highly accurate bridge circuit that can cope with only a small drift and a highly sensitive resistance change in application of a two-dimensional magnetic field.

  The two Wheatstone measuring bridges shown for a 2D magnetic field sensor device can be used for the angle sensor. By coupling the out-of-plane pretreatment magnetic field 38, ie, perpendicular to the chip substrate surface 36, the composite pinning direction can be preset. When the external magnetic field in the plane rotates 360 °, the two Wheatstone measuring bridges produce a sinusoidal output signal. As a result of the different pinning directions, 90 ° phase shifted sine and cosine signals are generated in the two measuring bridges 24x and 24y. As shown in FIGS. 2 (a)-(c), the structural elements 18 can have any geometric shape and have to be provided with pinning directions which are offset by 90 ° or 180 ° relative to each other Not necessarily.

  An example of a layer stack of the resistive element 14 is shown in FIG. 5 in particular, a layer structure suitable for the setting according to the invention of the magnetization direction of the so-called simple spin valve reference layer. A pinned layer consisting only of an antiferromagnetic layer (AFM) 86 coupled with a ferromagnetic layer (FM) 82 as a reference layer 92 is deposited on a starting layer (seed layer) 88 which can also function as an electrical contact layer Be done. Located on top of this, depending on the MR technology, is a thin metallic nonmagnetic interlayer of, for example, Cu (GMR) 84, or a thin insulating layer of, for example, MgO (TMR) 76. On top of this, a free ferromagnetic layer (FN) 82 as a detection layer 94, which is finally covered by a protective layer 90 of, for example, Ta, is arranged.

  In order to set the magnetization direction, the layer stack of resistive element 14 is heated to a temperature higher than the blocking temperature at which the exchange coupling between antiferromagnetic layer 86 and reference layer 92 disappears, and the layer stack is subjected to an external pretreatment magnetic field. Receive As a result of the structural element 18 (not shown here), a magnetic field component which sets the required magnetization in the reference layer 92 is generated parallel to the layer plane. After the layer stack cools to a temperature lower than the blocking temperature, the bond between the reference layer 92 and the antiferromagnetic layer 86 is restored, and stable magnetization is retained in the reference layer 92 even after the pretreatment magnetic field is turned off. The pinning acts to set the magnetization of the reference layer 92.

  A magnetic field pretreatment apparatus 50 including an oven 52 and a magnetic field generator 66 is shown in FIG. The oven 52 has a door 70 that can be opened and closed, through which the entire magnetic field generator 66 can be removed. For example, the electrically operable heating device 54 can heat the interior of the oven to a temperature above the blocking temperature, preferably above 200.degree. The magnetic field generator 66 comprises a permanent magnet 68, which consists of individual ferromagnetic parts providing a pole face 56 and an opposing pole face 58 by means of a magnet yoke. The magnetic field of the permanent magnet 68 is induced through the iron yoke 80 and penetrates the air gap between the pole face 56 and the opposing pole face 58. In order to adjust the strength of the pretreatment magnetic field 38, an air gap adjustment device 60 is provided, by means of which the variable air gap 34 can be set by the iron yoke 80, whereby the pole face 56 and the opposite pole face The strength of the pretreatment magnetic field 38 established between 58 and 58 can be varied. A pole spacing arrangement 64 serving for reliable induction of the pre-treatment magnetic field 38 in the soft magnetic structural element 18 improves the magnetic contact of the magnetic field sensor arrangement on the chip substrate 12 with the resistive element 14 and the soft magnetic structural element 18 Provided for

  An exemplary embodiment of a magnetic field pretreatment device 50 as schematically shown in FIG. 6 is shown in perspective in FIG. The coupling of the pinned magnetic field within the framework of the method of manufacturing the magnetic field sensor device 10 is schematically illustrated in the side views of FIGS. The magnetic field sensor device 10 includes a chip substrate 12 on which a resistive element 14 is deposited as a TMR stack having a plurality of thin ferromagnetic layers and antiferromagnetic layers. Each of the resistance elements 14 includes a contact layer 88 for supplying a current, two ferromagnetic layers 82 and an antiferromagnetic layer 86, a reference layer 92 directly adjacent to the ferromagnetic layer 86, and a nonmagnetic layer 84. And a detection layer 94 separated from the reference layer 92. A pretreatment magnetic field 38 vertically penetrates the structural element 18 through the surface 44, which penetrates the resistive element 14 and strays resulting in the magnetic alignment of the ferromagnetic layer 82, in particular of the reference layer 92. As the magnetic field 46 emerges through the boundary edge 20, it leads to the induction of the magnetic flux 78. The surface 44 may be flat, curved or otherwise formed. The lower and upper contact layers for making electrical contact with the resistive layer 14 are already arranged at this stage.

  In FIG. 8 (a), the structural element 18 is U-shaped and has flux induced cutouts 74 by which the magnetic flux 78 is deflected and thus inductively induced. Thereby, the magnetic flux 78 is abundantly supplied to the boundary edge 20 and appears as a stray magnetic field 46. In FIG. 8, the magnetic flux 78 is shown only schematically and in a simplified form in order to explain the basically achieved operating principle. The dimensions and flux paths shown serve only to explain the basic principle.

  In FIG. 8 b, the structural element 18 provides the induction of the stray magnetic field 46 adjacent to the resistive element 14 in order to achieve complete pinning of the ferromagnetic layer 82, in particular of the reference layer 92, A dedicated pole shoe 72 is formed to cause the concentration of the magnetic field 46 to increase.

  Finally, in (c) of FIG. 8, the structural element 18 is intricately configured. The structural element 18 has flux induced notches 74 and overlapping pole shoe edges 72 to achieve improved coupling of the induced magnetic flux 78 inside the resistive element 14.

  An exemplary embodiment of a manufacturing method according to the invention is shown in the cross-sectional view of FIG. The soft magnetic structural element 18 is separated from the resistive element 14 by the insulating layer 76 and disposed on the chip substrate 12. The resistive element 14 is composed of a layer stack of the ferromagnetic layer 82 functioning as the reference layer 92 and the detection layer 94, the nonmagnetic intermediate layer 84, and the antiferromagnet 86 connected to the contact layer 88. On top of this there is an insulating layer 76 on which the structural elements 18 are deposited. The structural element 18 has a flux-induced notch 74 and a pole piece 72 to achieve the induction of the resulting pinned field at the resistive element 14. The stray field lines are introduced into the resistive element 14 via the pole shoes 72 of the structural element 18 in order to align the ferromagnetic layer 82, in particular the reference layer 92, by applying a vertically aligned magnetic field to the chip surface 36. Ru. After pinning, the structural element 18 can be removed, for example by etching or another removal method, and the fabrication of the magnetic field sensor device 10 is complete.

  The effective pinned field at the location of the reference layer typically has only a low strength of 100 mT or less, but is sufficient to pin a simple spin valve layer structure. However, synthetic antiferromagnets of this kind in the reference layer usually require a rather strong magnetic field for pinning and can not be pinned by this kind of weak magnetic field. Synthetic antiferromagnet means a layer structure in which two or more ferromagnetic layers are separated by a thin nonmagnetic interlayer, and the exchange coupling for aligning the magnetization in the ferromagnetic layers acts between the ferromagnetic layers It will be understood. Thus, the synthetic antiferromagnet comprises, for example, a series of at least two thin layers of magnetic and nonmagnetic conductive material of Co and Cu, the thin magnetic layers being alternately magnetized, so that the resulting exterior Does not generate a magnetic field. However, by using synthetic antiferromagnets with non-equilibrium, ie different ferromagnetic layer thicknesses, in the reference layer, even at these low field strengths, pin this type of layer structure above the blocking temperature Can stop

The structural elements 18 can be deposited by plating and are usually 1 μm to 20 μm high. For this purpose, in particular, a NiFe structure, for example made of NiFe 8020, is used. The resistive element 14 to be pinned is close to the boundary edge 20 of the structural element 18. An area of about 5 μm can be pinned and the area to be pinned can be partially covered by the structural element 18. Oppositely pinned resistive elements 14 may be placed very close to one another. The resistive element 14 then has identical material properties, such as, for example, barrier resistance and the TMR effect. In this way, parallel Wheatstone bridge branches with different pinning directions can be configured identically in order to obtain an optimized offset value. The insulating layer can be made, for example, of SiN or Al ₂ O ₃ with a layer thickness of 30 nm to 5000 nm. After depositing the seed layer, the soft magnetic structural element 18 can be constructed by electroplating. The structural element 18 may be formed by a structuring method and may receive a vertical pretreatment magnetic field to effect pinning. After removing the soft magnetic structural element 18, the insulating layer 76 may be selectively opened to allow electrical contact with the resistive element 14. Using the proposed magnetic field pretreatment apparatus 50, in contrast to conventional pinning devices in which the magnetic field is applied parallel to the chip surface in the plane, the pinning is performed by the magnetic field 38 aligned perpendicular to the chip surface 36 It can be done. The pretreatment magnetic field strength may be adjusted by the adjustable air gap 34.

DESCRIPTION OF SYMBOLS 10 Magnetic field sensor apparatus 12 Chip substrate 14 Resistance element 18 Soft magnetic structural element 20 Soft magnetic boundary edge 22 Resistance element boundary edge 24 Wheatstone measurement bridge 26 Bridge resistance 28 Upper bridge arm 30 Lower bridge arm 34 Adjustable air gap 36 Chip substrate Surface 38 pretreatment magnetic field 40 measurement bridge contact surface 42 chip substrate lower side 44 soft magnetic structure surface 46 boundary edge stray magnetic field 50 magnetic field pretreatment device 52 oven 54 heating device 56 pole surface 58 opposing pole surface 60 air gap adjustment device 62 Chip substrate holding device 64 Magnetic pole distance adjusting device 66 Magnetic field generator 68 Permanent magnet 70 Oven door 72 Pole shoe 74 Flux induced notch 76 Insulating layer 78 Inductive flux 80 Iron yoke 82 Ferromagnetic layer 84 Interlayer 86 Ferromagnetic layer / ferromagnetic Body 88 contacts Layer 90 Protective layer / Insulating layer 92 Reference layer 94 Detection layer

Claims (14)

A method for permanent magnetization by pinning the magnetization of at least one ferromagnetic layer in a magnetic field sensor device (10) deposited on a chip substrate (12),
At least one ferromagnetic layer and viewed contains at least one antiferromagnetic layer, GMR or TMR is the magneto-resistive element at least one resistor element (14) of the chip substrate surface of the substrate (12) (36) Manufacturing steps above,
On the chip substrate (12), wherein adjacent to the resistive element (14), or partially overlap cormorants case, and depositing at least one structural element (18) is a soft magnetic element,
Heating the resistive element (14) to a temperature above the blocking temperature of the material of the antiferromagnetic layer and coupling with a pretreatment magnetic field (38);
Cooling the resistive element (14) to a temperature below the blocking temperature;
Removing the pre-treatment magnetic field (38).
It said to reach the blocking temperature exchange coupling err vanishing acts between the antiferromagnetic layer and the ferromagnetic layer,
Before Ki構 forming element (18) is to combined the pretreatment magnetic field before Symbol structural element (18) the substrate surface (36) vertically into and through, at the position of the resistive element (14) the substrate that penetrates the surface of the substrate (36) a direction different optionally parallel to the ferromagnetic layer for pinning the resistive element (14) of said resistive element (14) in some areas even without least in order to generate a magnetic field component parallel to the surface (36), is arranged,
A method characterized by To perform a permanent magnetization of at least one ferromagnetic layer of the resistance element in the same direction parallel (14) to the front Kimoto plate surface (36), two or more of said resistive element (14) before Ki構 associated with forming elements (18),
A method according to claim 1, characterized in that. To perform a permanent magnetization of at least one ferromagnetic layer of the resistive element in parallel with different directions (14) to the front Kimoto plate surface (36), two or more of said resistive element (14) before Ki構 associated with forming elements (18),
A method according to claim 1, characterized in that. The set magnetization directions of the ferromagnetic layers of the resistive element (14) are parallel or antiparallel to each other,
A method according to claim 3, characterized in that. To form at least one upper or lower bridge arm ho Itosuton measuring bridge (24) (28, 30), can be used at least two or more resistance elements,
The method according to any one of claims 1 to 4, characterized in that. The resistive element (14) comprises a GMR layer system and / or a TMR layer system,
The method according to any one of claims 1 to 5, characterized in that. At least one boundary edge of the front Ki構 forming element (18) (20) extends flat row or tangential to the boundary edge of the resistive element (14) (22), said resistive element (14) is pre Ki構 Overlap in some areas by the forming element (18), the overlap having a size of 5 μm or less,
The method according to any one of claims 1 to 6, characterized in that. Magnetic flux density of the stray field (46) is derived by the previous SL pole shoe protruding in the structural element (72) or-out flux guide notches (74), as amplified appearing,
The soft magnetic structural element (18) is formed;
The method according to any one of claims 1 to 7, characterized in that. It said resistive element (14) is of SiN or Al2O3 layer has a thickness of 30nm~5μm an insulating layer (76), is insulated from the front Ki構 forming element (18),
The method according to any one of claims 1 to 8, characterized in that. The structural element (18), the on-chip substrate (12), by depositing or building a soft magnetic material layer of NiFe with a layer thickness of 1 000Nm～20myuemu, electric plating and individual pre Ki構 Manufactured by lithographic structuring methods for structuring structuring elements (18),
A method according to any one of the preceding claims, characterized in that. When pinning process is completed, can be removed before Ki構 forming element (18) from said chip substrate (12),
The method according to any one of claims 1 to 10, characterized in that. A magnetic field pretreatment device (50) for magnetic pretreatment of resistive elements (14) of a magnetic field sensor device (10) deposited on a chip substrate (12),
The magnetic field pretreatment device (50) includes an oven (52) and a magnetic field generator (66) having a magnetic pole surface and opposing magnetic pole surfaces (56, 58) inside the oven (52) ,
At least one chip substrate comprising at least one structural element (18) which is a soft magnetic element and at least one resistive element (14) which is a GMR or TMR magnetoresistive element arranged on the substrate surface (36) (12), said front different directions of any parallel to Kimoto plate surface (36) to be vertically aligned and the resistive element (14) the substrate surface for pinning (36) the structural element (18 ) by the front guided processed field (38) by in order to achieve a magnetic pretreatment resistance element (14), between the front Symbol pole face and the front SL facing pole faces (56, 58) Placed,
A magnetic field pretreatment apparatus characterized in that. The magnetic field generator (66) comprises a permanent magnet (68) disposed in the oven (52), and the strength of the pretreatment magnetic field (38) is determined by an air gap adjustment device (60). Can be set by means of an adjustable air gap (34) between the) and the pole face and the opposite pole face (56, 58),
The magnetic field pretreatment device according to claim 12, characterized in that: A magnetic field sensor device for detecting the component of at least one external magnetic field (10), comprising a resistance element (14), the magnetic field sensor device according to any one of claims 1 to 11 Manufactured according to the method,
Magnetic field sensor device characterized in that.